256 lines
5.8 KiB
HTML
256 lines
5.8 KiB
HTML
<HTML
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><HEAD
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>Programming example</TITLE
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
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TITLE="The Linux SCSI Generic (sg) HOWTO"
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TITLE="sg_header, the original sg control structure"
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TITLE="Debugging"
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>The Linux SCSI Generic (sg) HOWTO</TH
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><H1
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NAME="PEXAMPLE">Appendix C. Programming example</H1
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><P
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>This appendix contains an example program. It is an abridged version of
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sg_simple2.c found in the <A
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HREF="sg3_utils.html"
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>sg3_utils</A
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>
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package. It send a SCSI INQUIRY command to the nominated sg device and
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prints out some of the response or outputs error information. Hopefully
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showing the error processing does not cloud what is being illustrated.
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<TABLE
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="PROGRAMLISTING"
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> #include <unistd.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/ioctl.h>
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#include <scsi/sg.h> /* take care: fetches glibc's /usr/include/scsi/sg.h */
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/* This is a simple program executing a SCSI INQUIRY command using the
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sg_io_hdr interface of the SCSI generic (sg) driver.
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* Copyright (C) 2001 D. Gilbert
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* This program is free software. Version 1.01 (20020226)
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*/
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#define INQ_REPLY_LEN 96
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#define INQ_CMD_CODE 0x12
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#define INQ_CMD_LEN 6
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int main(int argc, char * argv[])
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{
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int sg_fd, k;
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unsigned char inqCmdBlk[INQ_CMD_LEN] =
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{INQ_CMD_CODE, 0, 0, 0, INQ_REPLY_LEN, 0};
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/* This is a "standard" SCSI INQUIRY command. It is standard because the
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* CMDDT and EVPD bits (in the second byte) are zero. All SCSI targets
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* should respond promptly to a standard INQUIRY */
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unsigned char inqBuff[INQ_REPLY_LEN];
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unsigned char sense_buffer[32];
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sg_io_hdr_t io_hdr;
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if (2 != argc) {
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printf("Usage: 'sg_simple0 <sg_device>'\n");
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return 1;
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}
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if ((sg_fd = open(argv[1], O_RDONLY)) < 0) {
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/* Note that most SCSI commands require the O_RDWR flag to be set */
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perror("error opening given file name");
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return 1;
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}
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/* It is prudent to check we have a sg device by trying an ioctl */
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if ((ioctl(sg_fd, SG_GET_VERSION_NUM, &k) < 0) || (k < 30000)) {
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printf("%s is not an sg device, or old sg driver\n", argv[1]);
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return 1;
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}
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/* Prepare INQUIRY command */
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memset(&io_hdr, 0, sizeof(sg_io_hdr_t));
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io_hdr.interface_id = 'S';
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io_hdr.cmd_len = sizeof(inqCmdBlk);
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/* io_hdr.iovec_count = 0; */ /* memset takes care of this */
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io_hdr.mx_sb_len = sizeof(sense_buffer);
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io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
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io_hdr.dxfer_len = INQ_REPLY_LEN;
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io_hdr.dxferp = inqBuff;
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io_hdr.cmdp = inqCmdBlk;
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io_hdr.sbp = sense_buffer;
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io_hdr.timeout = 20000; /* 20000 millisecs == 20 seconds */
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/* io_hdr.flags = 0; */ /* take defaults: indirect IO, etc */
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/* io_hdr.pack_id = 0; */
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/* io_hdr.usr_ptr = NULL; */
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if (ioctl(sg_fd, SG_IO, &io_hdr) < 0) {
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perror("sg_simple0: Inquiry SG_IO ioctl error");
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return 1;
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}
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/* now for the error processing */
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if ((io_hdr.info & SG_INFO_OK_MASK) != SG_INFO_OK) {
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if (io_hdr.sb_len_wr > 0) {
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printf("INQUIRY sense data: ");
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for (k = 0; k < io_hdr.sb_len_wr; ++k) {
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if ((k > 0) && (0 == (k % 10)))
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printf("\n ");
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printf("0x%02x ", sense_buffer[k]);
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}
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printf("\n");
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}
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if (io_hdr.masked_status)
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printf("INQUIRY SCSI status=0x%x\n", io_hdr.status);
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if (io_hdr.host_status)
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printf("INQUIRY host_status=0x%x\n", io_hdr.host_status);
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if (io_hdr.driver_status)
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printf("INQUIRY driver_status=0x%x\n", io_hdr.driver_status);
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}
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else { /* assume INQUIRY response is present */
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char * p = (char *)inqBuff;
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printf("Some of the INQUIRY command's response:\n");
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printf(" %.8s %.16s %.4s\n", p + 8, p + 16, p + 32);
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printf("INQUIRY duration=%u millisecs, resid=%d\n",
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io_hdr.duration, io_hdr.resid);
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}
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close(sg_fd);
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return 0;
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} </PRE
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></FONT
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></TD
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></TR
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></TABLE
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></P
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><P
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>The sg_simple4.c program is an example of using mmap-ed IO in the sg3_utils
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package. An example of using direct IO can be found in sg_rbuf.c in the
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same package.</P
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></DIV
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>Prev</A
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WIDTH="33%"
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>sg_header, the original sg control structure</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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> </TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Debugging</TD
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